Re: [PATCH v4 1/7] coresight: etm4x: Fix event count decoding

[sashiko-bot@kernel.org]

> From: Leo Yan <leo.yan@arm.com>
> 
> TRCIDR0.NUMEVENT normally encodes the number of events minus one.
> From ETMv4.3 onwards, including ETE, a zero TRCIDR4.NUMRSPAIR instead
> means that no events are implemented and NUMEVENT is zero. The sysfs
> event controls currently interpret this combination as one event and
> allow writes to unsupported event fields.
> 
> Decode NUMEVENT after NUMRSPAIR and store the actual number of events
> in nr_event. Use the decoded resource count so that older ETM versions,
> where a zero NUMRSPAIR represents one resource pair, still report at
> least one event. Update both sysfs event controls to use the actual
> count and clear their event fields when no events are implemented.
> 
> Also correct the instruction event enable mask for the single-event
> case to use INSTEN[0]. The existing mask uses INSTEN[1], preventing
> event 0 from being enabled.
> 
> This change depends on the recent driver refactoring. With no reported
> failures, it is not intended for stable backporting.
> 
> Signed-off-by: Leo Yan <leo.yan@arm.com>

Sashiko has reviewed this patch and found no issues.

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